How to find the plane angle of dihedral angle

A straight line in a plane divides the plane into two parts, each part is called a half plane, and the figure composed of two half planes starting from a straight line is called a dihedral angle (this straight line is called an edge of a dihedral angle, and each half plane is called a face of a dihedral angle). The dihedral angle can be measured by its plane angle. Just say how many degrees the dihedral angle is. A dihedral angle whose plane angle is a right angle is called a straight dihedral angle.

The method of finding dihedral angle: take any point on the common line of dihedral angle as the endpoint, and make two rays perpendicular to the common line in two planes, and the angle formed by these two rays is the plane angle of dihedral angle.

The size of dihedral angle can be expressed by plane angle.

A dihedral angle whose plane angle is a right angle is called a straight dihedral angle.

Definition of two planes perpendicular: Two planes intersect, and if the dihedral angle they form is a straight dihedral angle, they are said to be perpendicular to each other.